Improved measurement of the shape of the electron

Abstract

The electron is predicted to be slightly aspheric [1], with a distorsion characterised by the electric dipole moment (EDM), d e . No experiment has ever detected this deviation. The standard model of particle physics predicts that d e is far too small to detect [2], being some eleven orders of magnitude smaller than the current experimental sensitivity. However, many extensions to the standard model naturally predict much larger values of d e that should be detectable [3]. This makes the search for the electron EDM a powerful way to search for new physics and constrain the possible extensions. In particular, the popular idea that new supersymmetric particles may exist at masses of a few hundred GeV is difficult to reconcile with the absence of an electron EDM at the present limit of sensitivity [4,2]. The size of the EDM is also intimately related to one 1

Exotic leptons: Higgs, flavor and collider phenomenology

“…Note that the Barr-Zee contributions to the EDMs scale in the same way with the charge of the vector leptons, Q χ , as the NP amplitude in h → γγ does. As we will show, bringing the 2-loop contributions in agreement with the most recent measurements of the electron EDM [62,63],…”

“…Measurements of these quantities result in very constraining limits, especially EDM measurements, which already probe electro-weak 2-loop contributions [62][63][64][65]. As a consequence, the mixing operators in these models must have very small coefficients or must be forbidden by an additional symmetry.…”

Precision Tests of Discrete Symmetries at Low Energies

“…EDM limits from selected experiments. The achieved experimental results for the neutron [24], the diamagnetic atoms 225 Ra [25], 199 Hg [26] and 129 Xe [27], the diatomic molecules YbF [28] and ThO [29] are within about one order of magnitude consistent with the expectations based on the figure of merit in eqn(3). As the neutron and diamagnetic atoms are not used to search for an EDM n theelectron, we use here η = 1 for evaluating M. Within this frame there are excellent perspectives to challenge the best electron EDM searches for a planned experiment on BaF with realistic parameters [30,31].…”

Absolute frequency determination of molecular transition in the Doppler regime at kHz level of accuracy

“…High precision and accuracy in measurement is required for searching for subtle physical effects and small discrepancies between the experiment and theory [1][2][3]. Spectroscopy of weak molecular transitions, like the O 2 B-band [4] line presented here or the quadrupole transitions in H 2 or D 2 [5], can provide valuable information about molecular structure [6] or verify quantum electrodynamics in molecular systems [7].…”